Lee, Haemin Lee, Dong-Myeong Lee, Cheol-Hun Lee, Jaegeun Lee, Kun-Hong 2024-01-19T15:04:38Z 2024-01-19T15:04:38Z 2022-01-25 2021-03 0008-6223 https://pubs.kist.re.kr/handle/201004/117285 We propose a reliable and accurate method that uses ultraviolet-visible-near infrared absorbance to measure the isotropic-cloud point (ICP) of carbon nanotube (CNT)/chlorosulfonic acid (CSA) solutions. This information is necessary to improve understanding of the isotropic-to-nematic transition of CNT/CSA solutions and to guide solution processing and characterization of CNTs. In this method, the ICP of CNT/CSA solutions is defined as the CNT concentration at which the absorbance at 600 nm is saturated. This wavelength was selected as suitable by considering the resonance ratio and mass absorption co-efficient. The reliability of the method was tested by comparing the ICPs measured using this method to those measured by a method that uses polarized optical microscopy and by a method that uses centrifugation. The results obtained using the three methods were consistent. An inverse proportionality between the ICP of CNT/CSA solutions and the CNT aspect ratio (AR) was confirmed; this result further confirms the reliability of our method. The AR of unknown CNTs can be predicted from the ICP of a CNT/CSA solution. Hence, this method provides a new tool to estimate the AR of unknown CNTs. (C) 2020 Elsevier Ltd. All rights reserved. English Pergamon Press Ltd. Determining the isotropic cloud point of carbon nanotube/chlorosulfonic acid solution using UV-vis-nIR absorbance saturation behavior Article 10.1016/j.carbon.2020.11.058 1 Carbon, v.173, pp.782 - 791 Carbon 173 782 791 N scie scopus 000625347900039 2-s2.0-85096972025 Chemistry, Physical Materials Science, Multidisciplinary Chemistry Materials Science Article PHASE-BEHAVIOR ABSORPTION-SPECTROSCOPY NANOTUBE FIBERS FLUORESCENCE DIAMETER LENGTH DISSOLUTION DISPERSION ARRAYS Carbon nanotubes Chlorosulfonic acid CNT/CSA solution Isotropic cloud point Isotropic Nematic transition Quantitative measurement